PROXIMATE TESTING METHOD OF MOISTURE MEASUREMENT FOR SUBSTANCES OF DIELECTRIC NATURE

Abstract

Contest. Variable chemical composition of the materials under research is a reason for so-called “type uncertainty” appearance, because the result of moisture measurement strongly depends from initial dielectric permittivity (type) of a material, and dielectric permittivity can be significantly different not only for different materials, but for different varieties of the same material. Development of new and modification of existing moisture measurement methods and development of new instrumental and secondary transducers is a problem of current importance for increasing the accuracy of moisture measurement. Objective. The purpose of this work is reduction the error of moisture measurement for bulk and liquid materials by new methods and means of moisture measurement development. Methods. A new method of moisture measurement had been developed with two additive, two multiplicative and two complementary testing influences on the sample under research. It foresees getting seven readings of a capacitance that should be plugged into the formula of a testing algorithm to get the moisture value. The method allowed to reduce material’s type influence on the result of moisture measurement and to increase accuracy of measurements. To make a new method of moisture measurement proximate, special instrument transducer had been developed. It allows simulation of additive testing influences on the material by using flat conductive plates of a certain thickness, introduced directly into a space between the electrodes. Results. The main purpose of experiments was to prove the capability of the new method of moisture measurement to work with experimental values of capacitances. New instrument and secondary transducers had been developed for that purposes. Obtained results helped to see that new testing algorithm has good conditionality when working with real values of capacitances with natural random variation. Conclusions. As a result we could see that maximal absolute error does not overcome 1.3 % of moisture content. It shows that substitution the direct adding of water with metallic plates does not decrease conditionality of calculated moisture value results, obtained using the new method of moisture measurement.